Peripheral Intrastromal Hydration Facilitates Safe, Deep Trephination in Corneas of Irregular Thickness.

PURPOSE: To evaluate the feasibility of regularizing the peripheral corneal thickness before deep trephination in highly irregular corneas undergoing deep anterior lamellar keratoplasty (DALK) by means of intrastromal hydration with saline. METHODS: This is an interventional case series including all eyes with irregular peripheral corneal thickness undergoing DALK for any indication between January 1, 2016, and January 1, 2017, at a single tertiary center in Forli, Italy. Before trephination, 1 mL of normal saline was injected intrastromally into each clock hour of peripheral thinning (determined using preoperative pachymetry) using a 30-gauge needle. A deep trephination of 400 to 450 µm was then performed, and DALK was completed as per our previously described technique. Primary outcome measures were perforation during trephination and intraoperative complications, with secondary outcomes of best corrected visual acuity and refraction. RESULTS: Peripheral intrastromal hydration was performed in 61 eyes of 61 patients. Intrastromal hydration ensured a safe trephination without perforation into the anterior chamber (AC) in 59 of 61 eyes. In the 2 cases in which perforation occurred, the perforation site was sutured with a full-thickness suture and the surgery was completed successfully. No cases required conversion to penetrating keratoplasty. Intrastromal injection of 1 mL of normal saline resulted in an increase in corneal thickness of 31%. After surgery, double AC was observed in 3 cases (4.9%), with all cases being managed successfully by air injection into the AC. CONCLUSIONS: Zonal peripheral intrastromal hydration is a feasible technique to enable safe, deep trephination even in corneas of highly irregular thickness.

Factors Predictive of Double Anterior Chamber Formation Following Deep Anterior Lamellar Keratoplasty.

PURPOSE: To identify risk factors predictive of postoperative double anterior chamber formation after deep anterior lamellar keratoplasty (DALK). DESIGN: Retrospective institutional cohort study. METHODS: The study group included all consecutive eyes undergoing primary DALK between May 2015 and October 2018 at Villa Igea private hospital (Forli, Italy). The indications for surgery were categorized as (1) keratoconus without scarring; (2) keratoconus with scarring; (3) non-keratoconus without scarring; and (4) non-keratoconus with scarring. Multivariate binary logistic regression analysis was performed, introducing, as independent variables, those that reached a significance level of less than .05 in univariate analysis. The main outcome measure was whether or not postoperative double anterior chamber (AC) occurred. RESULTS: A total of 591 eyes of 591 patients were included. The main indication for DALK was keratoconus (67.2%, n = 397), and pneumatic dissection was achieved in 72.9% (n = 431) of patients. Postoperative double AC was observed in 8.1% (n = 48) of cases. Age, intraoperative central DM perforation, type 2 bubble formation, and presence of scar in keratoconic and nonkeratoconic corneas were all associated with an increased risk of postoperative double AC formation in the univariate analysis. Manual dissection was not associated with double AC formation. The factors that remained significant in multivariate analysis were keratoconus with scarring (odds ratio [OR] = 3.56, P = .02), non-keratoconus with scarring (OR = 5.09, P = .002), intraoperative central perforation (OR = 6.09, P = .03), and type 2 bubble formation (OR = 14.17, P < .001). CONCLUSIONS: Scarred corneas of both normal and abnormal shape are independent risk factors for double AC formation following DALK, along with intraoperative perforation and the occurrence of a type 2 bubble.